Press



Dec. 3l, 1940.

F. H. SMITH PRESS Filed March 25, '1937 z/s TORNEYS.

Patented Dec. 31, 1940 UNITED STATES PATENT OFFICE PRESS Frank H. Smith, New York, N. Y.

Application' March 25, 1937, Serial No. 133,017

(Cl. (t-54.5)

3 Claims.

My present invention relates to presses and, more particularly, to presses in which either or both the work engaging ram and the platen may be actuated through an enclosed uid medium by 5 a mechanically operated piston.

The invention has for its principal object the production of a press wherein a variable or constant pressure may be applied to the material to be formed, as may be desirable for briquetting, extruding, forging or other pressing operations, and in which the piston is in constant movement, the pressures applied and the movement of the ram being under the control of the operator at all times.

Another object is the production of a press wherein the work engaging ram may be operated through an enclosed iiuid medium by a constantly driven mechanically operated piston, and wherein the pressures applied upon the ram at the will of the operator.

A further object is the production of a press wherein greater speed is obtained without the use of expensive and complicated clutches and the like.

To illustrate the salient features of my invention I have, in the following specification and the attached drawing, fully described and illustrated one embodiment thereof, and in which drawing- Figure 1 is an elevational view, partly in section, of a press embodying my invention;

Figure 2, a view in section, of a control valve;

Figure 3, a somewhat diagrammatic view illustrating a means for controlling the press; and

Figure 4, a fragmentary view showing a means for restraining the movement of the ram.

In the drawing the numeral I0 indicates an operating primary member of a press, and I I a work engaging secondary member, the former comprising a piston III and a head I0', and the latter a. piston II terminating in a ram II'. 'I'he primary member I0 and the secondary member I I are separated by an enclosed fluid medium I3 in a cylinder I4, the enclosure being made duid-tight by suitable packing glands I5. The member IIJ is connected by a. pitman I6 to a, crank shaft Il which is arranged to be rotated by any suitable means, such as a motor, not shown, through reducing gears I 8. The ram Il is slldably supported from the head of piston III, by bolts I9, which control the return of the ram I I'. 'I'he primary and secondary members just described, are mounted for reciprocal movement in suitable guides 2U carried by the main frame 9 of the press.

Also mounted upon the frame 9 is a boss 2| having an aperture therein for the reception of one end of a-shaft 22 the other end of which is secured in an outstanding lug 23 carried by the work engaging ram II. The shaft 22 has a reduced portion 22' which provides a suitable shoulder or stop 24 to limit the upward movement of the ram II and, a suitable guide for a spring 25 interposed between the boss 2l and a nut carried by the free end of the shaft 22.

The operation of the mechanism for controlling the movement of the ram during the idling strokes is as follows: Assuming the crank to be in continuous operation, the movement thereof will cause the ram head IIJ to likewise move a similiar distance because of the connecting rods or bolts I9. The surge tank being directly connected to the ram cylinder during such movements there is no pressure in the ram cylinder and, therefore, the Weight of the ram II will cause it to move with the rods I9. However, such movement o'f the ram II would cause the ram to interfere with the loading and unloading of the press and I, therefore, have provided the bolts 22, the lugs 2l and 23 and the springs 25, as previously described, to retain the ram II' in an elevated position and clear of the heads of the bolts I9 until the presy sure within the cylinder becomes greater than the pressure of the springs 25. In as much as the springs 25 are designed to Offset the Weight of the ram II', it will cause the bolts 22 to remain seated against the lugs 2| as at 24, until the power strokes are resumed. During the idling strokes the rods or bolts I9 will slide within their bearings in the ram I I'. During the power strokes the increased pressure within the cylinder will cause the ram I I' to be projected downward to the completion of the stroke and against the pressure of the springs 25. When the power stroke is completed the springs 25 and the bolts I9 cause the ram II' to be returned to the elevated idling position.

'I'he uid medium I3, which may be oil or water, is supplied through a pipe 26 which has a blow-off valve 2l mounted therein for a purpose i later to be described.

I have found that for certain operations it is highly desirable to provide a fluid balancer or pressure control for the ram and, in such cases, I may resort to a construction of balancer 3U, such as is illustrated and described in Patent No.1,473,

388, issued to me and to Alois K. Nowak, November 6, 1923. Such a balancer consists of a lower casing 3| in which slides a piston 32, the piston being enlarged to engage the portion 33 of a superposed structure 34, which comprises an enlarged portion 35 and a smaller portion 35. The piston 32 also has a stem 31 sliding in the smaller portion 36. The lower casing or chamber 3I is supplied with a fluid under pressure by a compressor 38. 'Ihe stem 31 is made with a small cross sectional area so that the high pressure in cylinder I4 may be balanced with relatively low pressure in cylinder 3l as is commonly understood. While the pressure control is, by way of example, shown vertically arranged, it may be disposed in any other manner provided the forces engaging pistons 32 and 31 oppose each other. The total force, of course, equals the pressure per square inch of the fluid times the cross sectional area of the surface of the piston in contact with the fluid.

In other pressing operations I have found it desirable, in order to obtain maximum speed under absolute control, to continuously drive the crankshaft I1 at constant speed. In the construction shown in thedrawing; I have done away with all of the usual friction clutches and the like, and use in lieu thereof a valve 40, connected in the pipe 25, and a surge tank 4I connected thereto. A valve 25 is provided between the valve 40 and the balancer 30 so that the same may be entirely shut off when desired.

The valve 4l), as shown, is a three way valve, one end connecting to the cylinder I4 through the medium of the pipe 26, the other end to the balancer, or to the blow-off valve 21 in the event the balancer is not used, and the third, or top, is connected to the surge tank 4I. 'Ihe valve 40 proper has a valve stem 42 which carries a valve i3 for engagement with a valve seat 44. Inasmuch as the valve must withstand great pressures, I have provided a protector for the valve and its packing in the form of a cup 45 which operates under'the action of a spring 46. Ample packing glands are providedat various points in the valve to insure proper sealing and operation of the valve.

The upper end of the valve stem 42 is projected through a packing gland 4l carried by a connection 48 secured to theY top of the valve casing. The connection 48 also connects to a pipe 49 which in turn is connected to the surge tank 4|. Two solencids 59 and 5I engage the free upper end of thevalve stem 42 and respectively move the valve stem 42 in opposite directions and provide a means for controlling the opening and closing of the valve i3 in a manner to be described.

By the arrangement just described it will be seen that by the use of the valve 40 the uid medium in cylinder I4 may be caused to pass into the surge tank 4I when the Valve 43 is opened, or, into the balancer 38 (in case the same is being used) when the valve is closed. The blow-01T valve 21 is mounted in pipe 25 between the valves 4f! and 23 so that any undue pressures may be dissipated thereby.

To control the displacement of the fluid medium incylinder i4 duringk the power strokes of the ram II', I provide a cam 52 which is mounted upon the crankshaft I1, a pair of contacts 53 and 54, and a push button 55. The push button is conveniently located and one terminal thereof is connected to contact 53 and the other to one terminal of the valve closing solenoid 50. The two solenoids are connected together as at 56 and 51 and to a switch lever 58, actuated bythe cam 52, through a suitable electric energy supply 59. The other terminal of the solenoid 5I isconnected to Contact 54.

In use my press operates as follows; Assuming the proper dies for forming the material are in position, the operator starts the crankshaft in rotation and positions the material to be formed over the lower die and presses the push button 55. The crankshaft being in constant rotation, the member I likewise is in constant reciprocation but, the valve 4I] being open, until the push button 55 is pressed, the fluid medium is surging back and forth into the surge tank so there is no pressure created within the cylinder I4. However, when the operator presses the push button 55 the valve 43 by means of the solenoid 50, is caused to close, provided the cam 52 has reached the correct position to establish a contact at 53, causing a pressure to be created within the cylinder I4. By increasing the pressure therein the ram II' is caused to engage the material to be formed. When the pressing operation is completed, the cam 52 establishes a contact at 54 which energizes solenoid 5I and causes the valve 43 to again open. It is to be noted that when the valve 43 is caused to be opened it is at a period when there is no flowing of the fluidl and the fluid is under no pressure.

Should it be desired to build or use my press without the balancer 30, the operation will be the same except that a fixed pressure will be' maintained Within the ram cylinder during the power strokes instead of a variable pressure as provided by the balancer. To close off the balancer the valve 26 is closed.

The operation of my press without the balancer is as follows: During the idling movements of the press the' valve 45 is opened allowing the fluid to pass freely to and out of the surge tank, in accordance with the movement of the crank. This results in practically no downward pressure being exerted upon the ram I I". When, however, the valve 40 is closed the pressure within the cylinder is greatly increased thereby causing the ram II to be projected downward against the pressure of the springs 25, and. into contact with the work sheets carried by the platen 'as will be understood.. The blowoff valve 21- will prevent undue pressures during the power strokes. adjusting the cam 52 with respect to the position of the crankshaft, opening and closing of the valve 40- may be controlled in timed relationV to the position of the piston I0.

Shouldy the operator desire a different pressure within the ram cylinder during the power strokes the valve 26 is opened and the balancer adjusted to give the desired pressure.

Thusit will be seen that I have evolved aV novel and practical press and particularly the control thereof at high. speed, wherein the piston, while in constant movement, does not engage the work until the operator so desires, which results in aY very much: faster press as well as a much cheaper pressto build.

While I have shown and described one practical embodiment of my invention, I wish it to be clearly understoodmy invention is not limitedto the constructions and combinations shown and that other constructions and combinations may be used without departing from the spirit and scopeof my invention.

I- claim:

. i. Afpresscomprising a cylinder having a pistonA and a worky engaging ram which are separated by a fluid medium, means for actuating said piston, means connecting said actuating. means andi the ram, said connecting means: being constructed and arranged to permit idle movement of the said piston relative to said ram, and means including a surge tank and valve for controlling displacement of the fluid in said cylinder at a deiinit-e point in the movement of said piston.

2. A press comprising a cylinder having a piston and a Work engaging ram which are separated by a fluid medium, means for actuating said piston, means connecting said actuating means and the ram, said connecting means being constructed and arranged to permit idle movement of the said piston relative to said ram, means for restraining movement of the ram during the idling strokes or" the piston, and means including a surge tank and a valve for controlling displacement of the uid in said cylinder at a denite point in the movement of said piston.

3. A press comprising a cylinder having a continuously reciprocating piston mounted therein and a Work engaging ram which are separated by a uid medium, means for actuating said piston, means connecting said piston and Said ram Whereby relative movement of the piston to said ram is provided, means for restraining movement of the rain during the idiing strokes of said piston, means including a surge tank and a Valve for controlling displacement of the iuid in said cylinder in timed relation to-the movement of said piston.

FRANK H. SMITH. 

